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Battery separator, fabrication method thereof

A technology of battery separator and composite separator, which is applied in battery pack parts, separators/films/diaphragms/spacers, circuits, etc. resistance increase and other problems, to achieve the effect of good electrical insulation, strong solvent resistance, and good high temperature resistance.

Active Publication Date: 2009-03-25
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the battery separator is laminated with a polyolefin layer and a heat-resistant layer, the bonding force between the polyolefin layer and the heat-resistant layer is small. When the battery is in abnormal conditions such as local high temperature during use, due to the huge thermal expansion coefficient The difference causes the heat-resistant layer polymer attached to the polyolefin substrate to fall off, so the battery is prone to short circuit under high temperature conditions and cause the battery to explode
In addition, since the battery separator is made of a laminated polyolefin layer and a heat-resistant layer, the film thickness of the battery separator cannot be effectively reduced. If the separator is too thick, the passage rate of lithium ions will be affected, and the internal resistance of the battery will increase. , and the separator is too thick, it will reduce the capacity of the battery

Method used

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  • Battery separator, fabrication method thereof
  • Battery separator, fabrication method thereof
  • Battery separator, fabrication method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0052] In step a, dissolve 4,4'-diaminodiphenyl ether (Shanghai Haiqu Chemical Co., Ltd.) and pyromellitic dianhydride (Shanghai Haohua Chemical Co., Ltd.) in organic solvent N, N'-dimethylacetamide (Shanghai Jingwei Chemical Co., Ltd.) to obtain a polyimide precursor solution; wherein the molar ratio of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride is 1:1, and the solvent N,N'- The weight of dimethylacetamide is 12 times of the total weight of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride; the temperature of the solution is controlled at 10-30 DEG C during the preparation process.

[0053] Step b Use a film applicator to coat the polyimide precursor solution prepared in step a on a clean and dry glass plate substrate with a coating thickness of 300 μm, cover with two layers of polyethylene non-woven fabric and soak for 4 minutes, and then apply it to the non-woven fabric A layer of polyimide precursor solution with a thickness of 300 μm was coated on the c...

Embodiment 2

[0057] In step a, dissolve 4,4'-diaminobiphenyl (Shanghai Jiachen Chemical Co., Ltd.) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (Beijing Bomi Technology Co., Ltd.) in an organic solvent N , N'-dimethylacetamide (Shanghai Jingwei Chemical Co., Ltd.) to obtain a polyimide precursor solution; wherein 4,4'-diaminobiphenyl and 3,3',4,4'-biphenyl The molar ratio of tetracarboxylic dianhydride is 1:1.01, the weight of solvent N,N'-dimethylacetamide is 4,4'-diaminobiphenyl and 3,3',4,4'-biphenyl tetra 15 times the total weight of carboxylic dianhydride; the temperature of the solution is controlled at 10-30°C during the preparation process.

[0058] In step b, the polyimide precursor solution prepared in step a is coated on a clean and dry glass plate substrate with a coating thickness of 400 μm, covered with three layers of polypropylene non-woven fabric and then rolled for 1 min to make The polyimide precursor solution can be fully soaked in the polypropylene non-woven fabr...

Embodiment 3

[0061] In step a, 1,2',3,3'-benzophenone tetracarboxylic dianhydride (Beijing Bomi Technology Co., Ltd.) and 3,3'-dimethyl-4,4'-diaminobenzidine Ketone (Shanghai Jiachen Chemical Co., Ltd.) was dissolved in the organic solvent N, N'-dimethylacetamide (Shanghai Jingwei Chemical Co., Ltd.) to obtain a polyimide precursor solution; wherein 1,2', 3,3' -The molar ratio of benzophenone tetracarboxylic dianhydride and 3,3'-dimethyl-4,4'-diaminobenzophenone is 1:0.99, solvent N,N'-dimethylacetamide The weight is 10 times of the total weight of 1,2',3,3'-benzophenone tetracarboxylic dianhydride and 3,3'-dimethyl-4,4'-diaminobenzophenone; preparation During the process, the temperature of the control solution is 10-30°C.

[0062] In step b, a layer of polyester non-woven fabric is covered on the clean and dry glass plate substrate, and the polyimide precursor solution prepared in step a is coated on the polyester non-woven fabric with a film applicator to a thickness of 500 μm to obtai...

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Abstract

The invention discloses a battery diaphragm and a preparation method thereof. The battery diaphragm is a porous battery septum and comprises polyimide and non-woven fabric. The porosity of the battery diaphragm provided by the invention is 30 to 50 percent, and the average pore diameter is 0.01-0.1 Mum, thereby ensuring that lithium ions pass through the battery diaphragm smoothly, and reducing hole resistance in a battery. When the battery is used, even if in abnormal situations such as local high temperature and the like, because the polyimide and the non-woven fabric are directly combined, the polyimide does not fall off from the non-woven fabric, the short circuit of the battery is not caused, and the safety performance of the battery is improved.

Description

technical field [0001] The invention relates to a battery separator, in particular to a battery separator for a lithium ion battery. The present invention also relates to a method for preparing the above-mentioned battery separator. Background technique [0002] The electronic information age has led to a rapid increase in the demand for mobile power. Compared with traditional batteries, lithium-ion batteries have the advantages of high specific energy, long cycle life, no memory effect, safety and pollution-free, and fast charging and discharging, making them widely used in portable electronics. Equipment, electric vehicles, space technology, national defense industry and many other aspects have broad application prospects. The application shows that lithium-ion battery is an ideal small green power supply. [0003] Lithium-ion batteries are composed of electrodes, electrolytes, and polymer separators. Between the positive and negative electrodes of a lithium-ion battery ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16C08J5/22C08J5/18H01M50/409H01M50/423H01M50/489H01M50/491
CPCY02E60/10
Inventor 江林谢守德
Owner BYD CO LTD
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